Field controlled magnetic thermal hysteresis in Co ∕ Tb multilayers

Experimental results proving that Co ∕ Tb multilayers show thermal hysteresis in the total magnetic moment are presented. [ Co ( 30 Å ) ∕ Tb ( 45 Å ) ] 8 was synthesized using dc magnetron sputtering. Due to antiferromagnetic coupling between the Co and Tb layers this system behaves like an artificial ferrimagnet. The measurement of magnetic moment ( M ) as a function of temperature ( T ) shows that magnetic phase transition occurs at different temperatures during heating (superheating) and cooling (supercooling) cycles resulting in a characteristic bow-tie shaped thermal hysteresis curve for M ( T ) . The width of the thermal hysteresis was measured to be around 90 K in an external magnetic field of 2000 Oe. Increasing the field to 4000 Oe reduces the thermal hysteresis width to about 40 K and above 6000 Oe the width disappears. Co ∕ Tb multilayers with thicker layers such as [ Co ( 40 Å ) ∕ Tb ( 60 Å ) ] 8 show the same trend. However, the width of the thermal hysteresis is generally smaller at a given magnetic field.